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<table width="100%" summary="page for OldMaps"><tr><td>OldMaps</td><td align="right">R Documentation</td></tr></table>

<h2>
Latitudes and Longitudes of 39 Points in 11 Old Maps
</h2>

<h3>Description</h3>


<p>The data set is concerned with the problem of aligning the coordinates of points
read from old maps (1688 - 1818) of the Great Lakes area.  
39 easily identifiable
points were selected  in the Great Lakes area, and their (lat, long) coordinates
were recorded using a grid overlaid on each of 11 old maps, and using linear interpolation.
</p>
<p>It was conjectured that maps might be systematically in error in five key ways:
(a) constant error in latitude; (b)constant error in longitude;
(c) proportional error in latitude; (d)proportional error in longitude;
(e) angular error from a non-zero difference between true North and the map's North.
</p>
<p>One challenge from these data is to produce useful analyses and graphical displays
that relate to these characteristics or to other aspects of the data.
</p>


<h3>Usage</h3>

<pre>data(OldMaps)</pre>


<h3>Format</h3>


<p>A data frame with 468 observations on the following 6 variables, giving the latitude
and longitude of 39 points recorded from 12 sources (Actual + 11 maps).
</p>

<dl>
<dt><code>point</code></dt><dd><p>a numeric vector</p>
</dd>
<dt><code>col</code></dt><dd><p>Column in the table a numeric vector</p>
</dd>
<dt><code>name</code></dt><dd><p>Name of the map maker, using <code>Actual</code> for the true coordinates of the points.
A factor with levels <code>Actual</code> 
<code>Arrowsmith</code> <code>Belin</code> <code>Cary</code> <code>Coronelli</code> <code>D'Anville} \code{Del'Isle</code> <code>Lattre</code> <code>Melish</code> <code>Mitchell</code> <code>Popple</code></p>
</dd>
<dt><code>year</code></dt><dd><p>Year of the map</p>
</dd>
<dt><code>lat</code></dt><dd><p>Latitude</p>
</dd>
<dt><code>long</code></dt><dd><p>Longitude</p>
</dd>
</dl>



<h3>Details</h3>


<p>Some of the latitude and longitude values are inexplicably negative.
It is probable that this is an error in type settting, because the table footnote
says &quot;* denotes that interpolation accuracy is not good,&quot; yet no &quot;*&quot;s appear in
the body of the table.
</p>


<h3>Source</h3>


<p>Andrews, D. F., and Herzberg, A. M. (1985).
<EM>Data: A Collection of Problems from Many fields for the Student and Research Worker</EM>.
New York: Springer, Table 10.1.  
The data were obtained from <a href="http://www.stat.duke.edu/courses/Spring01/sta114/data/Andrews/T10.1">http://www.stat.duke.edu/courses/Spring01/sta114/data/Andrews/T10.1</a>.
</p>


<h3>Examples</h3>

<pre>
data(OldMaps)
## maybe str(OldMaps) ; plot(OldMaps) ...

with(OldMaps, plot(abs(long),abs(lat), pch=col, col=colors()[point]))
</pre>


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